This invention pertains to stud welding and, more particularly, to the use of stud welding to form blind tapped holes having improved depth-thread ratios, all of which may be accomplished with thinner parts and thus less metal. Moreover, this invention relates to a new process to facilitate the joining of plates or the like by the use of blind tapped holes simplifying fabrication techniques while using less material. Preferably, such joining is accomplished by drilling a hole through a part, tapping the hole and closing and sealing one end of the hole by stud welding a stud thereover. A threaded connector inserted into the open end of the hole, then, may be used to secure a second plate or the like to the first.
Conventionally, such plates or other parts are attached or joined by a process which requires the drilling and then tapping of a blind hole in one of the parts. The blind hole is drilled to a depth which is near to the far surface of the part for maximum thread depth. It has been found desirable that the depth of threads for securely fastening such parts or the like should be 11/2 times the diameter of the bolt or threaded connector. If this ratio cannot be achieved then a thicker part must be employed. If a thicker part is employed then most of the additional material is wasted. A thicker part can, of course, be welded to the part but this then greatly increases fabrication costs. Thus, the part, when using the conventional method, must be thicker, to accommodate the blind hole, than the part used in applicant's method which is through drilled and tapped.
Therefore, the conventional process requires penetration accuracy drilling which is inherently disadvantageous. Another disadvantage with conventional methods is that as the blind hole is tapped, metal chips and shavings clog the hole or the threads. Consequently, cleaning steps are required including the air blasting or blowing out of the chips or shavings before the connector is inserted. Still another disadvantage is that the blind hole will frequently require finish tapping, or bottom tapping, with a still further cleaning operation following the finish tapping of the blind hole usually being necessary. A tapped through-hole is always easier and more economical to make and does not encounter the problems or potential problems and drilling and tapping blind holes. (Seek the TOOL ENGINEERS HANDBOOK of the ASTE published by McGraw Hill, 1949, page 807)